Web alignment detector



Jan. 11, 1944. D. c. STOCKBARGER ET AL. 2,339,204

WEB ALIGNMENT DE TECTOR Original Filed May 5, 1937 7 Sheets-Sheet l363;? nmpunsre wmpmm 36/ FIG. I.

Jan. 11, 1944. D. c. STOCKBARGER ET AL WEB ALIGNMENT DETECTOR 7SheetS-Sheet'Z Original Filed May 5, 1957 FIG-.3.

FIGZ.

I I I I I I I I I I I FIGS? I I I I I I I I Jan. 11, "1944. D. c.STOCKBARGER ET AL 4 WEB ALIGNMENT DETECTOR 7 Sheets-Sheet 4 OriginalFiled May 5. 1937 TDHLDR SWI-POEJPH Janll, 1944 DEC. STOCKBARGER ET AL2,339,204

WEB ALIGNMENT DETECTOR '7 Sheets-Sheet 5 origltLnal Filed May 5, 1957kNN a J Q \M Q mm J \N QM N \NN Q MM NM 8w R9 i 8N um I numb AW 8w 5% wI I r .lll C MQ Q RN Eu 3 M 3w mNN Qw Q Q T 0 VN mv wl! www Nu an 8N 3wJan- 11, 1944- D. c. STOCKBARGER ET AL 2,339,204

WEB ALIGNMENT DETECTOR Original Filed May 5, 1957 7 SheetS -Sheet 6 2/52/0 N J J m nia is... 11, 1944 WEB ALIGNMENT DETECTOR Donald C.Stockbarger, Belmont, and John L. Jones, North Billerica, Mass.,assignors to Stockton Profile Gauge Corporation, Lowell,

Mass., acorporation of Massachusetts Original application May 5, 1937,Serial No.

140,996, now Patent No. 2,220,736, dated November 5,1940. Divided andthis application October '7, 1940, Serial No. 360,094

6 claims.

This invention relates to web alignment detectors, and particularly todetectors for webs composed of material such'as paper and the likepassing through a machine performing an operation such as, for example,a printing press.

This invention is a division of the invention described in theapplication of Donald C. Stockbarger and John L. Jones, Seral No.140,996, filed May 5, 1937, for Apparatus for'detectlng web alignment,ieventuated into Patent 2,220,736, dated November 5, 1940.

Among the several objects of the invention may be noted: a

of parts, which will be exemplified in the structureshereinafterdescribed, and the scope of the application of which will be indicatedin the following claims.

Referring now more particularly to the accompanying drawings, in whichare illustrated several of the various possible embodiments of theinvention,

Fig. 1 isa diagrammatic side elevation of a printing press showingalignment controls in accordance with the present invention;

The provision of apparatus for detecting web alignment which interposesno mechanical obstruction to the movement of the web;

The provision of apparatus for detecting web alignment which is capableof accurate operation at web speeds up to and exceeding six hundred feetper minute, as encountered in modern highspeed rotary presses;

The provision of apparatus for detecting web alignment which issubstantially free of inertial forces, whereby misalignment may be morespeedily corrected;

The provision of apparatus for detecting web alignment which operatesupon actuation by predetermined indexpositions, or abnormalitiesthereof, of periodically repeatingpatterns upon the web, which patternsmay comprise either printed regions normally contained on the web, orspecially provided patterns, or both;

The provision'of apparatus for detecting web alignment which includes adetection of an abnormality in the position of the web,. a determinationof the direction of such abnormality, and the application of acorrecting influence properly suited-to the said direction of theabnormality;

The provision of web alignment detectors operating upon opticalprinciples, wherein detection is made of the normality or abnormality inposi:- tion of a periodically repeating pattern upon the web;

The provision '6: web alignment detectors ineluding photoelectricobserving means for abnormalities in alignment of the web;

The provision of apparatus of the class described which is relativelysimple and e'conomica in construction and in operation. 1

Other objects will be in partobvious-and in part pointed outhereinafter.

The invention accordingly comprises the elecircuit;

Figures 2 through 7 are fragmentary plan views of typical webs of paperin various conditions hereinafter to be described:

Fig. 8 is a diagram of an optical arrangement for a preferred lateralalignment control;

Fig. 9 is a cross section taken substantially along line9--9 of Fig. 8,showing a mask; v

Fig: 10 is a cross section taken substantially along line Ill-l0 of Fig.8, and illustrates'the image of the mask of Fig. 9, as projected onto aweb, the said web being properly aligned;

Fig. 11 is a view similar to Fig. 10, but illustrating the same elementswhen the web is laterally misaligned in one direction;

Fig, 12 is a view similar to Fig. 10, but illustrating the elements whenthe web is laterally misaligned in the other direction;

Fig. 13 is a cross section taken substantiallyalong line I,3-l3 of Fig.8, showing another mask;

Fig. 14 is a cross section taken substantially along line l4l4 of Fig.8, showing the image of the mask of Fig. 13 as projected on a web;

Fig. 15 is an electrical circuit diagram for the lateral alignmentcontrol of Fig. 8;

Fig. 16 is an exemplary electricalamplifier Fig. 17 is a .top plan viewof a preferred compensating roll;

Fig. 18 is a cross section taken substantially ....along line l8-I8' ofFi 17, showing-an outside ments and combinations ofelements, andfeatures of construction and operation and arrangements elevation of adual control arm;

Fig. 19 is across section similar to Fig. 18, but

showing an alternative position of a control arm;

Fig, 20 is a cross section taken substantially along line 20-20 of Fig.17, showing the inside elevation of said dual control arm;

Fig. 21 is a cross section taken substantially along line 2l-2l of Fig.17, showing the outsid elevation of a simple controlarm;

Fig. 22 is a cross section taken substantially along line 22-22 of Fig.17, showing the inside elevation of said simple control arm;

Fig. 23 is a cross section taken on line 23-23 of Fig. 18, showing apivot pin and drive nut;

Fig. 24 is a back elevation of the compensating roll of Fig. 17;

Fig. 25 is a front elevation of a paper roll shifting device;

Fig. 26 is a plan view of a fragment of the device of Fig. 25, beingtaken on line iii-26 of Fig. 25;

Fig. 27 is an electrical circuit of an alternative form of lateralalignment control;

Fig. 28 is a diagram of an optical system which may be used as analternative to a portion of the optical system illustrated in Fig. 8;

Fig. 29 is a fragmentary plan view of the web used in connection withthe optical system of Fig. 28;

Fig. 30 is an electrical circuit for use with the embodiment shown inFig. 28;

Fig. 31 is a diagrammatic side elevation of a lamp filament and support;

Fig. 32 is an optical diagram showing an alternative to the Fig. 28embodiment;

Fig. 33 is an optical diagram of still another alternative to the Fig.28 embodiment;

Fig, 34 is a cross section. taken substantially along line 34-44 of Fig,33, showing a mask;

Fig. 35 is a plan view of another mask useful in connection with theFig. 33 optical system;

Fig. 36 is a plan viewof the image of the mask of Fig. 35 as projectedon a web, the web being properly aligned laterally;

Fig. 37 is a view similar to Fig. 36, except that the web is laterallymisaligned in one direction;

Fig. 38 is a view similar to Figs. 36 and 37, except that the web islaterally misaligned in the other direction; and, i

Fig. 39 is a diagram of an electrical circuit for the lateral alignmentcontrol using the mask of Fig. 33.

Similar reference characters indicate corresponding part throughout theseveral views of the drawings. a

With modern high-speed rotary printing presses, the problem of controlof the moving paper or other web upon which the printing is being doneis a diificult one.

Attempts have heretofore been made to control the position and locationof the moving web through a printing press by means of mechanicalfeelers and like elements which engage the moving web itself. However,the easy tearing and breaking character of paper, which is the materialof which the web is usually composed, makes such control methods ingeneral unsatisfactory, since the feelers or like mechanism all tooeasily tear the web. This is particularly true when the web travels atthe high speeds encountered in modern rotary presses, such as sixhundred feet per minute. Further, the inertia of such mechanical webcontrol means makes it substantially impossible for them to respond withsufilcient speed to abnormalities in position of the web, and correctivemovements, if they are applied at all,

are applied only after such a delay that considerable wastage of webmaterial is brought about in the meanwhile.

Optical methods of web control-are in general more satisfactory, sincethey depend upon light phenomena, which have no inertia, and are thusresponsive with greater speed to an abnormality in the web position,Further, the light rays used for detection of abnormalities in positionof the web offer no mechanical or other obstruction to the movement ofthe web, and cannot tear or otherwise disfigure the web, as is the casewith mechanical feelers and the like.

However, up to the present time, no optical web control mechanisms havebeen provided which are capable of controlling the moving web withdesired accuracy, particularly at relatively high press speeds. Thepresent invention is, so far as we know, the first provision of suchoptical control systems. i

The present invention, in its broader aspects, is applicable not only tothe alignment of webs passing through printing presses, but to webspassing through machinery which performs operations on the web inaccordance with certain dimensional characteristics thereof, such ascutters, trimmers, folders, and the like, as will be pointed out ingreater detail hereinafter. However, in order to simplify theexplanation of the present invention, it will be described principallyin its application to printing presses.

There is accordingly shown in Fig. 1, in diagrammatic form, amultiple-press, rotary printing press,,which is equipped with thealignment control features of the present invention. Referring moreparticularly to Fig. 1, index character R, indicates a paper or websupply roll, that is supported in a cradle device indicated generally atnumeral i. Proceeding from the roll R is a web W of paper, on which theprinting is to be accomplished. From the roll R the web W passes aroundan idler roll 2, a tensioning roll 3, and idler roll 4, I and 8, to acompensating roll Cl hereinafter more fully to be described. From thecompensating roll' Cl the web W passes between the two cylinders 9 andH! of a first press Pl, receiving therein a desired impression. From thepress Pl, the web W passes around a second compensating roll C2, andthence between the cylinders H and H of a second press P2. From thesecond press P2 the web W passes around an idler roll I3, a thirdcompensating roll C3, an idler roll it, and into a slitter mechanismindicated gener ally by letter S. For present purposes, the operationson the web will be considered to have terminated when the web isdelivered to the slitter S, although, as will be described more fullyhereinafter, the slitter S is itself provided with alignment controls inaccordance with the present invention.

Index character Al indicates, in Fig. 1, a diagrammatic lateralalignment detection device, which, operating through a motor MI, drive aroll-shifting device indicated generally by numeral B5 (to be describedin greater particular hereinafter) in the cradle I supporting the rollR. Lateral alignment detector Al, together with its motor MI and deviceI5, serves to perform a first, relative lateral guiding operation on theweb W, in order to provide that the web W, as it passes to the idlerrolls 1 and this substantially laterally aligned for the press Pl.However, in order that the web W may be accurately aligned, laterally,before it passes into the press Pl, a second lateral web alignmentdetector A2 is provided. This detector A2, operating through a motor M2,controls the compensating roll CI, in a manner hereinafter to bedescribed, so that if the web W is at all displaced from its desiredlateral course as it passes the detector A2, a correction issubstantially immediately applied by the compensating roll CI in orderto correct the travel of the web W. The web W is thus delivered to thepress Pl in perfect lateral alignment. Since, ordinarily, no printedmatter appears on the web W prior to its passage through the first pressP! (with the tion, andv the general manner in which they to work, sothat before many feet of web have second press P2 deliver itsimpressionon the web W in a precise lateral arrangement with respect to the matterprinted on the web by press Pl. For this purpose, a lateral alignmentdetector A3 is provided in juxtaposition to the web W between thepresses PI and P2. The lateral alignment detector A3 controls a motorM3, which in turn operates on the compensating roll C2.

From the'press P2, the now completely printed web W passes to theslitting mechanism indicated by letter S. It will readily be seen thatit is necessary that the slitting mechanism be precisely positionedlaterally with respect to the printed matter on the web. Hence a lateralalignment detector A4 is provided, and this detector, acting through amotor M4, controls the operation of compensating roll C3 in such amanner that the web W reaches the slitter mechanism S in proper lateralposition.

The foregoing cursory description of 1 indicates the various controlsemployed in the preferred embodiments of the present inven- 0 operate toassure the proper guiding of the 3 web through the multiple presses. Thescheme of operation, it will be seen, is to detect an abnormality intheposition of the web at any desired location, and then automatically toapply a correcting influence such that abnormality is corrected in theminimum possible time. In other words, while an abnormally positionedregion of the web may recorditself on an alignment detector as such, andwhile that particular abnormally position region will then go on andpass through the press in abnormal position, such abnormality in themeanwhile will have set the correcting mechanism passedthe detector theabnormality has been corrected;

Basically, the system or method provided by the present invention forthe purpose of detecting the lateral alignment of amoving web comprisesoptically detecting whether or not a predetermined part of the web'is ina predetermined index position, either constantly or intermittently atpredetermined times relative to the beginning of the cycle in which thedetection takes place, determining whether any displacement of thepredetermined part of the web from the predetermined index position ispositive or negative such as to the right or to the left, and producingan electrical signal or controlling the flow-of electric current in thecircuit of a correcting means in accordance with th algebraic sign ofthe displacement if there is a displacementat the time of the detection.The alignment of the web may then be corrected with appa'ratus of knowntype, outside thescope of the present' invention, in accordanc with thsignal developed by the detector. The above described detection may berepeated either constantly or during each successive cycle or during amajority of cycles at predetermined equal relative times after thebeginnings of the respective cycle in which detection occurs. Webalignment correction may be made each tim detection occurs if correctionis needed. 15

g 3 The part of the 'web inspected for alignment detection purposespreferably comprises a pattern of periodically repeating characteron-one 1 or the other or both surfaces of the web. A lat eral alignmentdetector is hereinafter described for inspecting such tern. I

may be an art design or printed words, for example, and thepredetermined part of the pat-" ternat which detection occurs may be anedge of an art figure or the top of a line of printed words, forexample. The phrase periodically repeating pattern" is also usedto-include a continuous pattern such as a continuous line runningparallel to an edge of the'web or such as an edge of the web itselffTheperiodically repeating pattern may be a special pattern printed on'theweb for the sole purpose'of alignment detection such as a dot or a linelocated outside any other printed areas which may be on the web; andsuch special patterns may if desired be located to coincide with partsof thewebwhich are subsequently to be removed by trimming or otherwiserendered unobjectionable;

Alternatively, the periodically repeating pattern need not be a printedpattern, but may comprise, for example, a series of perforations ofperiodically repeating characters-in the'material of the web, or aseries of regions on the web treated so as to make them transparent ortranslucent if the rest of the web is relatively opaque, or opaque ifthe rest of the web is relatively translucent or transparent. Thepattern need only' be of such a character that it presents a differentlight reflectivity or light transmissibility from the body of the webitself.

Figures 2 through 7 aid in visualizing what is meant by the termsperiodically repeating pattern as used in the preceding fewparagraphs.Figure 2, for example, shows a fragment of a paper'web W as itordinarily comes from the roll R, and'represents either the obverse orthe .reverse of the web. It is seen that the web W has I spots I! may belocated on the web in a region that is to become the binding margin of abook page, for example, or on an edge of the web that is later to betrimmed ofi, or the spots I! may be printed in a disappearing ink thatremains visible only long enough for alignment detection pur-" poses.

For maximum convenience, the row otspots I1 is not printed on the webprior to its passage through the first press Pl the web then beinglaterally controlled before it enters the press PI by alignmentdetectors inspecting. the edge of the web. In other words, referring toFig. 1, lateral alignment detectors Al and A2 are of the edgeinspectingtype, but since the pressPl provides a periodically repeating pattern onthe web W in the form of a row of spots IT, for example, lateralalignment detectors A3 and A4 may be andpreferably are types thatinspect the periodically repeating pattern. If the aforesaid specialprint a periodicallyrepeating pat The periodically repeating pattern'ontheweb ing mechanism is used to put the pattern on the web W, however,instead of the press Pl, or if the web in the roll R is pre-printed withthe pattern, then one or both of the lateral alignment detectors Al andA2 may be of the pattern-inspecting type, depending (in the formerinstance) upon the location of the said special printing mechanism.

Fig. 4 shows the obverse side of the web W after it has passed throughthe first press PI. The press Pi has imprinted upon the web W a numberof lines l8 of characters such as letters and numbers. Forsimplification, the lines are shown in Fig. l, and in subsequentfigures, as,

solid black lines. The lines I8 are arranged into groups or regions l9,which areseparated by unprinted spaces 20. Each of the groups i9,considered as a group, represents a pattern on the web W, and by thevery nature of the press cylinders 9 and Ill, and the manner in whichthey imprint the regions IS on the web W, said regions i9 recur atperiodic intervals (at least as often as once for each complete rotationof the cylinders 9 and I) on the web W. Hence the regions H! are classedas periodically repeating patterns" as above defined.

The reverse side of the web W is not ordinarily printed in the .firstpress Pl. Printing on the reverse side of the web W is ordinarily donein the second press P2, after which it has the appearance, for example,as shown in Fig. 5. Like the obverse shown in Fig. 4, the web W has beenimprinted with a number of lines l8 arranged in periodically repeatinggroups l9 separated by unprinted region 20. Thus, in the example shown,both obverse and reverse sides of the web W are provided withperiodically repeating patterns.

If two colors are wanted in the finished printing, and but one side ofthe web W is to be printed, then the second press P2 may be used toprint the second color, with suitable interchange of the printing andbacking cylinders. For example, the obverse side of the web W as itproceeds from the second press P2, set up as a color press, isindicated, for example, in Fig. 6. Here it will be seen that in additionto the matter appearing in Fig. 4, portions of the unprinted spaces 20have been filled with additional printed matter 2|, which-may, forexample, be in a color other than that of the printed region It. In Fig.6, the periodically repeating pattern may now be considered to consistof the combination of a group of lines l8 and their associated regions2|, or of the groups of lines l8 or the groups of lines 2| takenseparately, providing the detection system is of differential colorsensitivity, if lines i8 and 2| differ in color.

If two or more colors are wanted in the finished printing, and bothsides of the web W. are to be printed (even if one side has but onecolor), then additional presses over the two presses PI and P2 shown in.Fig. 1 are ordinarily needed, and alignment controls are preferablyprovided for each of these additional presses. Alignment controls, forexample. are of particular utility in securing accurate registry ofoverlapping color impressions in multi-color (such as threeorfour-color) picture printing, where multiple presses are involved.

Ordinarily, the special periodically repeating pattern provided foralignment detection purposes, such as the spots l1, need appear only onone side of the web W. However, in some instances it is advantageous tohave this pattern on both sides of the web. In this case such a patternon the reverse side of the web may be provided (1) in the web Winitially, as it comes in the form of roll R, (2) by the same specialprinting mechanism hereinbefore referred to, or a duplicate of it, or(3) by the press P2 as the reverse of the web W receives its firstprinting impression. Fig. 7 shows such a special pattern in the form ofa row of spots "A, similar to the row of spots I! in Figures 3, 4, and6. It is important, when a special pattern such as the spots HA isprovided on the reverse of the web W, that it align accurately with thespecial pattern (such as the spots H) on the obverse of the web W, so

that one lateral alignment detector inspecting the obverse of the webwill not buck against another lateral alignment detector inspecting thereverse of the web.

For lateral web alignment the detection is applied in such a way as todetermine whether or not a web edge or a pattern edge or both edges havewandered from their true or desired course, due to non-uniform webtensions for example, and the correction is applied in such a way as toremove effectively the cause of the wandering of the edge of the web orof the sequence of patterns with respect to the edge of the web or both.It is not necessary to detect and correct web alignment and patternalignment simultaneously nor with the same apparatus, nor is itnecessary to detect and correct either alignment once each successivecycle. Detection and correction may 'occur several times atpredetermined relative in tervals during each cycle of any predeterminedor random fraction of the total number of cycles which fraction may beunity, or they may occur only once during each of said cycles ifdesired. It is clear that the required relative frequency of detectionand correction will depend in any case on the magnitude of the tendencyto wander, on the degree to which the correction is to be applied and onother things.

The preferred system for lateral alignment detection in connection withthe present invention, using the principles of pattern inspection, isillustrated in Figures 8 through 15. A system of the type indicated inFigures 8 through 15 may be used, for example in locations A3 and A4 inthe diagrammatic illustration, Fig. 1, and in locations Al and A2 (orone of them) if the pattern is on web W prior to its passage through thefirst press Pl, as hereinbefore described.

The preferred lateral alignment system illustrated in Figures 8 through15 makes use of the rowof spots ll on the web W, as shown in Figures 3,4, 6 and 7. For this preferred system, the spots I! are each of squareshape and the same size, and are spaced apart, on a common center linerunning parallel to the edge of the web W, distances equal to their ownwidths. The spots I! are preferably printed on with ink or pigment (suchas black) which reflects discernibly less light than the surrounding,unprinted regions of the web W. In Fig. 8, which is an edgewise view ofthe web W, the spots I! are given a considerable elevation, so thattheir function with respect to the remainder of the apparatus may beunderstood; in practice, it will be understood, the spots H. are only ofthe thickness of printing ink.

As appears from Fig. 8, there is mounted above the web W a pair of.optical systems indicated generally. by numerals 22 and 23. The opticalsystem 22 is the lateral web alignment detector proper, while theoptical system 23 is for the purpose .of generating an alternatingcurrent used with the lateral alignment correcting means, will-beexplained hereinafter. The two'optical systems-22 and 23 are identical,except for the apertures in certain masks. Each system comprises a lightsource 24, which may suitablybe an incandescent filament bulb in whichthefilament is concentrated into a small area. In each system 22 and 23,a lens 25 focuses an image of the filament of light source 24' intoasecond lens 26. Positioned just in front of each lens 25 is a mask,indicated by numeral 21 in system 22- and by numeral 28 in system 23.The front lenses 26 focus images of certain apertures in the masks 21and 28 on the web W. In each system 22 and 23, the respective lightsources 24, and lenses 25 and 26, are arranged on an optical axis whichis preferably, although not necessarily, perpendicular to the plane ofthe web W, and the masks 21 and 28 are perpendicular to these opticalaxes (or parallel to the web W, in any even Arranged on optical axeswhich intersect the points of intersection of the axes of the systemsjust described and the-web W, for each system 22 and 23, arephotoelectric detection systems comprising collecting "lenses 29 andsuitable photoelectric cells 30A and 303. The lenses 29 project raysemanating from the images on the web, of the apertures in masks 21 and28, on the receptive cathodes of the photoelectric cells 30A and 303,respectively.

The mask 21 for the optical system 22 is shown in plan view in Fig. 9.The mask 21 has two parallel rows of uniformly spaced rectangularopenings or apertures. The apertures in one row are indicated by indexcharacters 3|, while the apertures in. the other row are indicated byindex characters 32. It will be understood, however, that the apertures3| and 32 are individually all preferably of the same size. The openings3| and 32, in their respective rows, are displaced from each other inthe direction of the row center-lines by an amount equal to the shortdimension of-a'single aperture, and the two rows are displaced in thedirection at right anglesto said center line direction by an amountwhich causes the projected images of the apertures-3| and 32 on the webW, in the optical ystem12" Y of Fig. '8, to be separated by a distancepreferably I ust equal to the width ofjthe. spots on the web W. Thisarrangement is indicated ii -Fig; 10, in which rectangles 33 are theimage's ofjaper- 'tures3l', as projected-by the lens 26, and rectangles34 are the images of the apertures 32. The widths-of the individualapertures3| and 32 are such that thewi'dths of their projected images 33and 34, along theirrespective'row center lines, are'preferably justequal to-the widths of the individual .spots I1. It will be noted thatthe two rows- 3| ancl 32 are arranged in a-staggered.

relation,- eachvaperture '.(except the end aperturesl being disposedalong its respective center line'in such manner that its sides areeffectively c'ontinuationsof the opposite sides of two adjacentapertures in the opposite row. In' theembodiment shown, three apertures-3|- form one row while threeapertures 32 form the other. row, but-thenumber three is not critical and may be increased or decreaseddependinmior example, upon the sensitivity of the photoelectricdetectingsysfi m employed. The lengths of-the indithan a maximum of sixor so times the width. 2

of the row of spots l1.

The mask 28 for the optical system 23 of Fig. 8v is shown in plan viewin Fig. 13. It contains a single row of parallel rectangular apertures35 centrally positioned along a common center line. The width of each ofthe apertures 35, along the common center line, may be equal to thewidth of the apertures 3| and 32 of mask 21, along their respectivecenter lines; in any case, the width of each aperture 35,'a10ng thecommon center line, is such that the width of its image 36 on the web W(Fig. 14) is equal to the width of each of the spots l1. The apertures35 are preferably all of the same length, and the length is such thattheprojected images 36 of said apertures line of the row of spots H on theweb W. Further,

the optical systems 22 and 23 are so positioned that, when the web W isin lateral alignment, the center line of the row of spots l1 liesmid-way between the center lines of'the rows of images 33 and 34, forthe optical system 22, and-coincides with the center line of the images36, for.

the optical system 23. These arrangements are indicated in Figures 10and 14, respectively. Furthermore, the optical axes of the two systems22 and 23 are displaced from each other, in a direction along thedirection of motion of the web W, in such'a manner that when one of thespots I 1 exactly coincides with one of the images 36 (i. e., theleading and trailing edges of said spot 11 are coextensive with theforward and rear edges of theimage 36) then at exactly the same time,the leading and trailing edges of another one of thespots H are in exactregister with the forward and rearward edges, respectively, of eitherone of the images 33 or one of the images 34. For present purposes, itmakes no difierence whetherthe images 33 or the images 34 are chosen forthis last condition. By such an arrangement, spots I! cross the images36 in the same phase relationship that said spots l1 cross vthe selectedrow of images 33 or 34,- and in an out-of phase relationship'with theother row of images 34; or 33. In Figures 10 and 14,. the inmaintainedbetween images The electrical circuit in which the photoelectric cells30A and 30B of the optical systems 22 and 23,

- of which lead to asuitable vidual apertures 3| and 32, in a directionat right angles to. the center lines of the rows, are all equal, and aredetermined by the amount of lateral displacement it is expected toencounter in the web. In the embodiment as shown.

respectively, are connected, is indicated in Fig. 15.. Cell 30A isconnected in series with a battery 31A across a resistance 33A, theterminals alternating current amplifier 39A. The design andcharacteristics of the amplifier 39A are within the abilities of oneskilledin the art of photoelectric cell ampliflers,

ever, a suitable amplifier circuit is shown, to-

gether with its exemplary constants, in Fig. -16.

be described hereand are not set forth in great detail herein for thatreason. By way of example, howpled amplifier having a two stage voltageamplifier using the so-called type 57" tubes, and a.

two stage power amplifier using the so-called type 46 tubes, the laststage of the power amplifier being a push-pull circuit. With theconstants shown in Fig. 16, it has proved to be satisfactory to use, asthe photoelectric cell 30A, a "visitron type AV" cell, with. theresistance 38A having a value of 100,000 ohms and the battery 31A havinga potential of 22 volts.

The photoelectric cell 303 of optical system 23 is milarly connected, inseries with a battery 31B, across a resistance 3813, the terminals ofwhich are in turn connected to a suitable amplifier 393, which may alsobe of the type shown in Fig. 16, for example.

The output leads of an amplifier 39A are connected to the field 40 of amotor 4!, which may be, for example, of common universal design foroperation on either direct or alternating current. The output leads ofamplifier 39B are connected to the armature 42 of the motor 4|. Motor 4|is the motor Ml, M2, M3, 01' M4 of Fig. 1, depending upon which lateralalignment system is being considered. As indicated in Fig. 1, motors MI,M2, M3, and M4 are associated with the respective compensating rollswhich correct lateral misalignment; the nature of this connection, andof the operation of the compensating roll, will be more fully developedhereinafter.

The operation of the lateral alignment detector as thus described is asfollows:

Referring first to the operation of the optical system 22, or lateralalignment detector proper:

So long as the web W is in proper lateral align- I ment, the row ofspots I! continuously passes between the two rows of images 33 and 34heretofore described. The individual spots do not cross any of theimages 33 and 34, and hence do not vary the light reflected therefrom tothe photoelectric cell 30A. The light reflected from the images 33 and34 to the photoelectric cell 30A, it is to be noted, depends in quantityupon the reflection characteristics of the web W. In general the web Wreflects more or less diffusely. The spots I! are printed in an ink, orother substance, which reflects less light than does the web W itself.Or, in the alternative, the spots I! may be printed with an ink or othersubstance that reflects more light than does the web W itself. Theprimary intention is that there shall be a differential reflectivitybetween the spots I1 and the surrounding area of web W. In all cases inwhich the differences in said reflection char.- acteristics areunusually small, steps must be taken to increase the differential orelse the overall sensitivity of the apparatus as may be required.Furthermore, in general, cases will arise in which the detection can bemade more positive through the introduction of selectively absorbinglight filters so that the web is effectively illuminated by light ofcertain spectral characteristics such as red light, for example. The useof selecrespect to the web W, this passage of the spots ll across theimages 33 will result in the variation or modulation of the amount oflight reaching the photoelectric cell A, and, because of theintermittent character of both the spots H and the images 33, thismodulation will be of a periodi cally varying character setting up analternating current in the photoelectric cell 30A. The frequency of thealternating current is dependent upon the speed of travel of the Web W,one complete alternation being produced each time a spot I1, and itssucceeding blank space, trav erses one of the images 33. The severalimages 33, it will be seen, act in parallel in this respect, and thus soserve to increase the amount of modulated light falling on thephotoelectric cell 30A without in. any way affecting the frequency ofthe modulation.

The periodic variation in the amount of light reaching the photoelectriccell 30A, which is connected in series with the battery 33A and theresistor 38A, causes a periodic variation in the amount of currentflowing through the resistor 38A. Since the input terminals of thealternating current amplifier 39A are connected to opposite ends of theresistor 38A the alternating current component in the voltage dropacross the resistor 38A produced by the variation in the current flowingthrough the resistor 38A causes the amplifier 39A to deliveralternating-current power, of suitable magnitude, to the field 40 of themotor 4|. The fundamental frequency of the alternating current powerso.produced is the same as the fundamental frequency of the periodicvariation in the amount of light reaching the photoelectric cell 30A.

The fact that the photoelectric cell 30A may be receiving unmodulatedlight (such as is reflected from the momentarily unaffected images 34,for example) at the same time that it is receiving modulated light fromthe images 33, is of no consequence, since the response of saidphototively absorbing light fllters may be particularly advantageous inweb alignment detection when the web W is printed with one or morecolored substances.

If the webW becomes misaligned, or wanders, to the left, then thecondition pictured in Fig. 11 willbe observed. The row of spots i! now,instead of passing between the rows of images 33 and 34 withoutaffecting either one of them, now passes in such a manner thatsuccessive spots intersect or pass across the images 33. Because nf-theclifierential reflectivity of the spots l1, with electric cell 30A isthen a direct current response and this introduces no alternatingcurrent component in the voltage drop across the resistor 38A.

Motors such as the one indicated at 4| in Fig. 15 are ordinarilydesigned to be operated on sinusoidal alternating current, but unlesssuitable steps are taken current from the amplifier 39A will not besinusoidal. If the amplifier 38A amplifies without distortion of thewave form, the output currentmay be expected to have the Wave form ofthe alternating current component of the voltage drop acros the resistor38A, and said voltage drop can be made to have substantially the waveform of the light modulation produced by the motion of the spots I!across images 33 as hereinbefore described, The shape of the spots I!and of the images 33 (and 34) can be calculated in such manner that thewave form of the modulation can be controlled, as in the reproduction ofsound in talking motion pictures, but this is usually impracticable forseveral reasons, and hence, therefore if the motor 4| does not functionsatisfactorily on nonsinusoidal current, all undesirable harmonicsshould be removed by means of a filter network having a hightransmission for alternating current of the fundamental frequency, suchas a band-pass filter, for example.- It is recognized that alternatingcurrent amplifiers may have filter networks possessing theaforementioned characteristics, and, therefore, it

- is assumed that the amplifier 39A is so designed.

If the web W wanders or deviates or becomes of amplifiers of lateraldeviation of the alternating current powerdelivered by the amplifier 38Ato the motor with respect to the power delivered by the a'mpli-.

pictured in Fig. 12 will be observed, instead of the condition picturedin Fig. 11. The only differen between Fig.- 11 and'Fig. 12 is that inFig. 12

the modulation of light reaching the photoelectric cell 30A is producedby'the passage of spots across the images 34, rather than the images 33.

Electrically, the effectis the same-as that described which relates toFig. 11. However, since the images 34 are spaced at a diiferent relativelocation than the images 33, the peaks of alternating current producedacross the resistance 38A will occur at difierent times. This timerelationship will be developed more fully hereinafter.

' The operation of the optical system 23, hereinbefore designated asan'alternating current generator, will now be described. In general, itis similar to the operation of the optical system 22, with the exceptionproduced by passage of the spots across the images'36 (see Fig. 14)regardless of the deviation or wandering of the web W, within limitsdetermined by the lengths of the images 36. This passage of the spots I!across the images 36 means that modulated light, of the same wave formas that produced in the optical system 22, will be delivered at alltimes to the photoelectric cell 333, and this willin turn cause theimposition of a' relatively constant form of alternating currentcomponent in the voltage drop across the resistor 38B. This alternatingcurrent component in the, voltage drop across the resistor 38B isamplified by the amplifier 393, which is in many respects similar to theamplifier 39A, and the amplifier 3913 thus delivers alternating currentpower to the armature 42 of motor 4|. As in the case of amplifier 39A,amplifier 393 may desirably have a. filter network for affecting thewave form of the output alternating current, to make it suitable forrunning the motor 4|.

Because the'same spots actuate the photo-' electric cells 303 and 30A,and because the widths of the images 33, 34 and 36 are all the same, the

fundamental frequencies of the alternating current power produced by theamplifiers 39A and 3913 will be the same, Because of the longitudinalspacing requirements for the optical systems 22 and 23, as hereinbeforementioned-the outputs 39A and 393 will be in phaseif it isv modulationof the light from the images 33 that is affecting the photoelectric cell30A (or, in

other words, if the web is misaligned to the left).

Or, on the. other hand, if the-modulation of light reaching. thephotoelectric cell 30A is produced by passage of spots across the images34 (inthe case web to the right), the

will be 1800ut, of phase fier 393. The motor 4| is of suchr'aharac'teristics that when its field and-armature are. respectivelyexcited by the. iii-phase I currents, itrotates in one direction,whilewhenits field and armature arerespectively excited by theout-ofphase'cur rents, it rotates inthe other direction.

- In the foregoing discussion it is assumed for simplicity that thephase displacements between inputsignals; and respective output currentsin the amplifiersI39A and39Bare identical. The

principle is unaffected by this assumption. In

tion of the equipment is substantially asrecited.

that light modulation is now requires several times as much poweras thefield 43, and therefore the amplifier39B must be deany case the distancebetween the optical .sys

It is now seen that, with the system described,

tion, while lateral deviation of the web Win the other direction causesthe motor 4| to run in the other direction. If the web W is runningtrue, as shown in Fig. 10, then since the photoelectric cell 30Areceives no modulated light, the amplifier 39A delivers no alternatingcurrent power to the motor field 40, and hence the armature of the motor4| does not move at all.

As has heretofore been intimated, and as will be described more fullyhereinafter, the motor 4| controls a compensating roll mechanism in suchmanner that when it rotates in one direction or the other, it tends tocorrect the misalignment of the web, laterally, in the proper direction.

It will be seen that the amount (not frequency) of modulation of thelight reaching the photoelectric cell 30A depends upon the relativeareas of the individual spots ll that pass through the images 33 or 34,and that this relative area in turn depends upon the extent of lateraldisplacement. For example, if the lateral displacement is but slight,then, as indicated in Figures 11 and .12, only part of the area of eachspot passes across the respective images 33 or 34. If the lateraldeviation is great, then the entire area of each spot ll willcrosseither image 33 or 34. The amount of photoelectric current mod-1ulation as thus produced, affects the amplifier 39A in such manner thata related amount of alternatingcurrent power is delivered to the field40 .of the motor 4|. In other words, the greater the lateral deviation,the stronger the alternating current signal delivered to the amplifier39A, and the greater the'alternating current power delivered to themotor 4|. Since the speedof rotation of the motor 4| depends upon theamount of power delivered to it, greater lateral deviation of the web Wwill cause faster rotation of the motor 4|, and consequently more rapidcorrection of the lateral deviation. This factor is im'- portant in theoperation of the press as a whole, because it means that greater lateraldeviations, which are more wasteful of web material, will be reduced.more rapidly than small deviations, which are not so serious from thestandpoint of waste.

The characteristics of the amplifiers 39A and 39B are made such that atall operating speeds of the press, sufficient power is delivered to thefield and armature 42 of motor 4| to insure the performance described.It-should be noted thatin general the armature 42 of the motor 4|signed-with this purpose in mind.

While the'lateral alignment detection systemthus described is preferredfor use with presses of the type herein principally concerned, it may bewidely modified and take several highly vary?- ing form's,-of whichseveral will 'greaterdetail hereinafter.

v The preferred form of compensating roll for making corrections of themisalignments detected by the lateral alignment detectors hereinbeforedescribed, will next be. explained. Rolls such as the one now to bedescribed are indicated by'the various referencecharacters C C2,- C3,etc., in

the general layout of the press'comprisingFig. 1.

In the preferred compensating roll, corrections are madev on the movingweb, both for its lateral and its longitudinal deviations, by means of asingle idler roller, whichfrictionally engages the be described in vthese figures, and more particularly to Fig. 17, I

numeral I88 indicates the single idler roller just mentioned. The rollerI88 is mounted on a shaft #89, the ends of which are received insuitable frictionless bearings I90 and IN mounted in arms I92 and I93,respectively. The arm I92 is simplest in construction, and will first bedescribed.

, It comprises a simple radial arm extending from a hub I94 which issecured by set screws I95 to a shaft I96 which extendsthe width of thepress. The roller I88, it will be understood, is preferably slightlylonger than the Width of the web. ()ne end of the shaft I96 is rotatablyreceived in a bearing I91, while the other end is likewise rotatablyreceived in a bearing I98. Shaft I98 has a portion I99 of reduceddiameter at the end ,which enters the bearing I98.

Both extreme ends of the shaft I96 are preferably provided with collars200 through which extend taper pins I for holding the shaft l98 againstsidewise motion in the bearings I9? and I99.

The other end of the roller comprises a collar 202, which is secured tothe shaft I96 by set screws 203. From the collar 202 extends a bracketor arm 204, in which is received a stud 205 provided with a bearingsurface 206. A screw 201 secures the stud 205 against rotation in thearm 204. The axis of the stud 209 is parallel to the axis of the shaftI96. Rotatably mounted on the bearing portions 206 of stud 205 is acollar 208, from which extends a radial arm 299. The.

roller bearing I9I is mounted at the far end of arm 209.

Referring now to Fig. 18, it will be seen that the bracket or arm 204has at its extreme end a pair of parallel projections 2I0. On the outerfaces of the two rojections 2I0 are mounted roller or like frictionlessbearing elements 2H, and these bearings 2II serve to mount therebetweena lead screw 2I2, which extends through the projections 2I0 and acrossthe space therebetween. At its lower end, the lead screw 2I2 isconnected by a suitable coupling 2I9 to a flexible shaft 2I4. Threadedon the lead screw 2I2 is a nut 2I5 which has a cylindrical portion 2 I6extending rearwardly, its axis being parallel to the axis of the stud205.- Portion 2I6 receives a roller 2I'I, and the roller 2I'l is held inposition on the portion 2I6 by a washer 2I8 and a screw 2 I9, asindicated in Fig. 23. The roller 2I'I slides up and down in a slot 220provided therefor in arm 209.

It will now be seen that if the lead screw 2I2 is rotated, the nut 2I5will move up and down said lead screw, relative to the bracket or arm204, and that motion of the nut 2I5 in the manner described will in turncause rotation of the arm 209 pivotting on stud 205. By way ofillustration, Figures 18 and 20 show the relative position of the arms204 and 209'when thenut 2I5 is at the bottom of the lead screw 2I2; Fig.19 shows the relative position of the arms 204 and 209 when the nut 2I5is at the top of the lead screw 2I2. The relative motion of the rollerI88 thus brought about by turning the lead screw 2I2 in a tiltingmotion. and results in an adjustment of the angle made by the axis ofroll I88 with the axis of shaft I96. When the nut 2I5 is in its centralposition on lead screw 2I2, the arms 204 and 209 are so positioned,relative to each other, that the axis of the roller I88 is parallel tothe axis of shaft I96.

The bearings I90 and ISI for the ends of shaft I89 of roller I88 arepurposely made in such a manner as to permit the tilting of the rollerI88 in the manner described, such as self-aligning ball bearings.

Returning again to Fig. 17, it will be seen that the collar 202 andbrackets 204, are pro- I vided with a forwardly extending flange orcollar 22I. ,Additional set screws 222 are de sirably provided in thecollar 22I, for securing the assembly firmly to the shaft I96. The faceof collar 22I receives one end of a tension or coil spring 223 that iswrapped around the shaft I96. The other end of the coil spring 223 isfirmly mounted in the face of a collar 224 which rotates upon theportion of reduced diameter ass of the shaft :96. The collar 224 issecured against longitudinal movement relative to the shaft I96 bypositioning it between the bearing I98 and the shoulder resulting fromthe portion of reduced diameter I99. Extending downwardly from thecollar 224 is a sector-shaped gear 225, the lower periphery of which isthreaded, as indicated at numeral 226 in Fig. 24, to engage the threadsof a worm wheel 22?. The worm wheel 221 is in turn mounted on a shaftthe end of arcuate slot 229.

Numeral 229 indicates an arcuate slot that is provided in the collar224, and numeral 230 indicates a radial pin that is mounted in the shaftI99 in position to engage the ends of slot 229. Normally, the pin 230 ispositioned to abut end of slot 229.

The operation of the compensating roll as thus described in the finishedpress is as follows:

As has heretofore been intimated, the roller I88 frictionally engagesand idles with the moving web. The bearings I91 and I98 are sopositioned that the shaft I96 is supported with the roller I88 in thedesired engagement with the web. It will be assumed, for the moment,that the nut 2I5 is located midway on the screw 2I2. A flexible shaft2I4 connected with the lead screw 2I2 is coupled with the shaft of motorM (Fig. 15) of the lateral alignment detection system (this motor isvariously designated as M2, M3, and M4 in Fig. 1).

If the lateral alignment detector now detects a lateral misalignment,this will result in the rotation of the shaft of motor M in a directiondepending upon the direction of lateral misalignment. Rotation of theshaft of motor H in turn rotates the lead screw 2I2 by the connectiondescribed, and rotation of the lead screw 2I2 moves the nut 2I5 up anddown thereon, causing relative rotation of arm 209 on bracket 204. Thenet result of this movement is to tip or tilt the axis of rotation ofthe roller I88. By tilting the roller I88, the direction in which theweb is proceeding is altered, and by altering this direction, thelateral misalignment is corrected. If the direction of lateralmisalignment is against the travel of the web, the extra pressure on theweb resulting from the correcting tilting of the roller I88 istemporarily transferred to spring 223, by the reaction through pin 230in its normal position of rest against In a brief time, however, spring223 returns to its present position, thus applying the full lateralcorrection required in a resilient manner. The correction of a lateralmisalignment with the direction of.

travel of the web relieves normal web tension, and hence no resilientapplication of the 'correc-r tion is needed.

Still referring to Fig. 1, it will be seen that the first lateralalignment detector Al operates through a motor Ml which affects directlythe roll-shifting device IS on the paper roll cradle I. In this respect,the system operatedby lateral alignment detector AI is different fromthe systems operated by the other lateral alignment detectors. Thisimplies no difference in the construction of the lateral alignmentdetector AI itself, but merely the device upon which it operates andthrough which it introduces its correc-.

tion. The roll-shifting device operated by lateral alignment detector'Alis indicated more particularly in Figures and 26.

The roll-shifting device I5 is generally ofa 20 type frequently providedfor paper rolls, and comprises a bearing portion 23! for receiving the,

. shaft of a paper roll, which bearing portion 23| is mounted on a block232. The block 232 is in turn supported on pins 233 which slide horizonstally in the frame 234 of the cradle. A lead screw 235 is mounted on theblock 232, and co operates with acylindrical nut 235A secured to theframe 234. A hand wheel 235B'and a worm wheel 236 are mounted on the endof the lead screw 235. .It will be seen that when either the hand wheel235B or the worm wheel 236 is turned, the block 232 moves laterallyrelative to frame 234, and hence changes the lateral alignment of theweb W coming from the paper roll. The bearing portion 23| includes adrum and cooperating brake shoes indicated generally by numeral 23lA, asis customary in devices of this character. The brake shoes are adjustedby a hand wheel,23|B

to regulate thetension in the web W leaving the roll. 7 I

The wormwheel 236 is engaged by a worm 23'! ona shaft 238 supported in asuitable bearing 239 mounted on the block 232. The shaft 238 isDepending upon the direction of rotation of motor Ml (which is in turndetermined by the direction of misalignment detected by the lateralalignment detector Al), the worm 231 will drive the worm wheel 236 insuch manner as to rotate the lead screw 235 and shift the block 232laterally, in exactlythe same manner as if said correction had'beenapplied through manipulation of the hand wheel 2353 in the mannerheretofore 65 practiced in connection with this type of appaa ratus.

- Fig. 27 indicates an alternative lateral alignment detector circuitwhich is in some respects a simplification of the circuit shown in Fig,15.

It will be recalled, by reference to-Fig. .8, that the optical system 23and photoelectric cell 303, together with its connected amplifier 393,all were described as an alternating current generating system. In Fig.2'7, this photoelectric alternating current generating system iseliminated, and replaced by a simple, ordinary-form of alternat ingcurrent generator indicated by numeral 242'. This alternating currentgenerator 242 is mechanically driven from some rotating part of the 70.

press, such .as one of the'press cylinders, so that I the generator 242produces current at a fundamental. frequency corresponding to the fundamental frequency of the current produced by -the photoelectric System 22(Fig. 8) and applied to 76 .driven by the motor M I through a universaljoint 46 240 and a telescoping joint 24l.

the field 40 of the motor 4|. The generator 242 is connected direct tothe armature 42 of the motor 4|. The circuit feeding the field 40 is thesame as in Fig. 15. I

The operation of this alternative embodiment of Fig. 27 is substantiallyidentical to the operation of the preferred lateral alignment detector,except that the armature current is supplied with mechanically generatedalternating current, from the generator 242, instead ofphotoelectrically generated alternating current, from the optical system23, photoelectric cell 303, etc. This embodiment may accordingly bedesignated as one in which the armature current is me-,

chanically generated, instead of photoelectrically generated. Thisembodiment should be used only when a careful control of thelongitudinal alignment of the web is maintained,.since longitudinalmisalignment, if great enough, might result in an unwanted phasedisplacement, between the field and armature voltages of the motor 4|.

Alternating currents can be generated, with certain favorable setups oftype, by using the "printed matter itself 'in an optical-photoelectricsystem such as that shown in Figures 28 through 31, inclusive. ingl'ightand dark areas constituting the lines of printed matter themselvesuponthe web W.

These lines of printed matter are indicated. with their usual numeral l8in Figures 28 and 29. Referring now more particularly to Fig. 23, nu-

merals 243A and 2433 indicate a pair of incanto the printed matter onthe web W that one of the images 241A and 2413 is at all times within aprinted region; in other words, the, distance d (Fig. 28) is such thatat no time is it possible for both image 241A and image 2413 to lie inan unprinted area. A photoelectric cell 248A looks.

- atthe image 241A through a collecting lens 249A,

while a similar photoelectric cell 248B looks at the image 2413 througha collecting lens 249B.

Fig. 30 shows the electrical circuit in which the photoelectric cells.248A and 2483 are connected. Referring to Fig. 30, it-will be seen thatthe two photoelectric cells 248A and 2483 are connected'in parallel, andfunction in the cir-- cuit as a single cell. It is merely as ifthephotoelectric cells 248A and 2483, together connected in parallel, aresubstituted for'the single photoelectric cell 303 in the alternatingcurrent generator side of the circuit of Fig. 15. The usu-- al battery31B and resistance 38B and amplifier 39B are provided, and the output ofthe amplifier 393 can be used in any desired manner, for example, inconnection with an alignment detection and correction system.

If necessary, more than two complete optical systems as indicated inFig. 28 may be provided.

in order that at least-one filament image is at all times focused on aregion including printed lines I. In this detection system, in whichsynchronism is an important feature, it'is impor-' tant that'the printedlines l8 be equi-distantly spaced and that unprinted areashave'len'gths; measured along the length of the web 'W, such Use is nowmade of the alternate indicated above.

that were they filled with lines l8, all lines on the web W would beequi-distantly spaced. The distance d (Fig. 28) between light spots istherefore a whole multiple of the spacing of the lines The operation ofthis alternating current generator is as follows: When the web moveslongitudinally, the passage of lines I8 through or across the images241A and 2413 produces a flicker or modulation in the reflected lightreaching the photoelectric cell 248A or the cell 248B, or both, andtherefore the current flowing through the resistor 383 contains analternating current component and the voltage drop across the resistor383 contains an alternating current component. of this alternatingcurrent generator is precisely the same as that of the preferredembodiment, as

The fact that one photoelectric cell 248A or 2483 may be receivingunmodulated light during apart of the time is of no consequence sincethe response cf said cell is then a direct current response and noalternating current component in the voltage drop across the resistor383 results. As'in the case of the preferred embodiment, it is desirablethat the ampliiier 39B of Fig. 30 be provided with a filter net-work orother suitable means for regulating the wave form of the outputalternating current.

Fig. 32 indicates an alternative construction that may be substitutedfor the optical system shown in Fig. 28. The only change, in thisinstance, is that asingle photoelectric cell 250 is provided, which cell250 receives a light from both images 241A and 24113. This isaccomplished by suitably positioning the lenses 249A and 249 B. Thesingle photoelectric cell 250 now receives the modulated light from bothimages, and is preferably connected in a circuit identical to that ofFig. 30 except that only one photoelectric cell is used. In other words,the circuit conbe either the cell ma, the cell 2483, or the cell 250,depending upon which embodiment is used with the mask type of lightprojector shown in Fig. 33. t

All of the alternative embodiments heretofore described are concernedwith alternate methods of generating alternating current power for thearmature 42. of the motor 4|, the lateral alignmentdetector proper ofthe preferred embodiment having been left unchanged. Fig. 33, togetherwith Figures 35 through 39, serves on the other hand to illustrate analternative form of From this point on, the operation lateral alignmentdetectorproper. For this alternative embodiment, the mask 254 of theFig. 33 optical system is replaced by a mask 251 as shown in Fig. 35.The mask 251 is provided with three substantially square apertures 25B,and these apertures are. of such size and shape that their nections nowbecome identical to those shown in Fig. 15, with the singlephotoelectric cell 25!! replacing the photoelectric cell 303.

In the embodiments of Figures 28 and 32, it is not necessary that theimage on the web W be that of a coil filament 244 as shown. For example,Fig. 33 shows a single optical system (which is used in duplicate ineither the Fig. 28 or Fig. 32 embodiment), in which a lamp 25l of theconcentrated filament type is provided. A lens 252 focuses an image ofthe filament of lamp 25! on a lens 253, in such manner as to fill thelens 253 with light. Numeral 254 indicates a mask which is positionedbetween the lenses 252 and 253, as close to the lens 252 as possible.The

lens 253 focuses images of apertures in the mask 254 on the web W. s

The mask 254 is indicated in plan view in Fig. 34. It will be seen thatit is provided with a plurality of apertures 255, which constituteparallel long narrow rectangles. The size and disposition of therectangular apertures 255 is such that these apertures, projected by thelens 253, will form images on the web W, which images exactly overliethe printed lines l8 on the web W. In other words, images of theapertures 255 are now substituted for the filament images 241A and 2413of Fig- 29. The aperture images operate in exactly thesame manner ingenerating altemating current, as do the images of the coil filaments241A and 2413. In Fig. 33, a single photoelectric cell 256 is shown;this photoelectric cell will images on web W are of size and shapeidentical to any three consecutive selected spots I! of the row of spotsI1 heretofore described. The row of spots 11 is again used for lateralalignment detection, as in the preferred lateral alignment detector. Theidentity in size, shape, and disposition, of the images of apertures 258in mask 25'! with the spots I1, is shown in Fig. 36, where the saidimages are indicated by numeral 259.

Fig. 36 shows the preferred normal condition to be obtained, when theweb W is in proper lateral alignment. It will be seen that in thisnormal arrangement, the center line of the row of spots I1 is displacedfrom the center line of the row of images 259 by an amountequal to halfthe width of the spots (or the images) in other words, as the web Wmoves, the maximum area overlapped is one-half the total area of theimages. The center lines of the images 259 of the spots I! are,

- however, parallel.

The photoelectric cell 256 (Fig. 33) is arranged to look at the images259 through a collecting lens 26H. Under normal conditions of properlateral web alignment, the cell 256 will receive uniform unmodulatedlight from one-half of each of the images 259, and modulated light fromthe other half of said images 259, as successive spots 11 passthereacross. If lateral misalignment should occur, in such manner thatthe web W is misaligned to the left, however, the condition shown inFig. 37 will be brought about. In Fig. 3'7, it will be noted that thecenter lines of the spots l1 and finages 259 are now displaced by suchan amount that the spots I! no longer cross over any part of the images259 at all, but merely pass tangent thereto. This means that thephotoelectric cell 256 will now receive nothing but uniform unmodulatedlight, since the lack of any intersection of the spots I! with theimages 259 means that no modulation will be brought about.

of the images 259 now exactly coincide. With the condition of Fi 38, itwill be seen that a maximum amount of modulated light will reach thephotoelectric cell 256, because now the spots II are passing across theentire areas of the images 259, and eifectively greatly modulating thelight reflected therefrom to the photoelectric cell 256.

Referring to Figures 36, 37, and 38 together, it will be seen that thesystem is such that if normal lateral alignment is maintained, amodulated current of normal magnitude is produced by the photoelectriccell 256; if lateral misalignment to the left takes place, the amount ofmodulated current is reduced, while if lateral misalignment to the righttakes place, the amount of modulated current is increased. v

Fig. 39 shows the circuit by which this varying amount of modulatedlight reaching the photoelectric cell 256 is translated into aneffective control. Referring to Fig. 39, it will be seen that thephotoelectric cell 256-is connected in series with a battery 26l and theseries combination is connected across the ends of a resistor 262. Theresistor 262 is in turn connected to an amplifier 263, such as is usedin previous embodiments. The output of the amplifier 263 is fed into asuitable rectifier 264, .whichis' capable of changing the alternatingcurrent component of the output current of the amplifier 263 to a directcurrent. Numeral 265 indicates a resistor that is connected across theoutput of the rectifier 264. One of the output wires then goes to thesliding contact 266 v of a potentiometer 261, across the ends of whichis connected a battery 266.

Numerals 269 and 216 indicate the oppositely facing magnets or coils ofa relay 21I to be described,in greater detail hereinafter. The coils.269 and 216 are connected in series, and the mid- Numeral 214 indicatesthe armature of the I relay 2", and this armature 214 is normally nectedto a reversible motor 216 as indicated in Fig. 39, the position of thearmature 214 determines the relative polarity of the power fed .to thearmature of the motor 218, and hence by movement of the armature 214under the influence of either coil 269 or coil 216, the direction ofrotation of themotor 218 may be controlled.

With the armature 214 in its central or neutral connection with neitherthe fixed contacts 216 nor the fixed contacts 211, and hence the motor218 does not operate.- I

' The operation of the circuit of Fig. 39 is as follows: The slidingcontact 266 of resistor or potentiometer 261 is set at such a positionthat no current flows through either of thecoils 269 or 216 when the webalignment is correct, and, therefore, under this condition the armature214 is in a neutral position and the movable contacts 215 do not connectwith either of the fixed contacts 216 ,orthe fixed contacts 211. is

The arposition, however, the movable contacts 215 make true because thevoltage drop across the resistor 265 is opposed by an equal voltage'dropapplied by the potentiometer .261. and battery 266 in combination. If,now, the web W wanders to the left,

looking in the direction of travel of the web, and the condition of Fig.37. is observed, then the voltage drop across the resistor 265 becomesless than the voltage supplied by the potentiometer 261 and currentflows through the rectifier 213 and coil 216 and consequently thearmature 214 is drawn over so that the movable contacts 215 connect withtheflxed contacts 211, and the armature of the motor 216 thus receivespower and rotates in one direction.

If, on the other hand, the web W wanders to the right, and the conditionobserved in Fig.

38 is observed, then the voltage drop across the resistor 265 is greaterthan the voltage supplied by the potentiometer 261 and current flowsthrough the rectifier 212 and coil 269 and consequently the armature 214is drawn over so that themovable contacts 215 connect with the fixedcontacts 216 and power is supplied to the motor armature to enable it torotate in a reverse direction. The magnitude of ,the voltage drop acrossthe resistor 265 is determined by the magnitude of the alternatingcurrent voltage drop appearing across'the resistor 262 as a result ofthe reception of modulated light by the photoelectric cell 256 and,therefore, the position of v the armature .214 is determined by themagnitude 251. It is seen, therefore, that when the web W is correctlyaligned,. the armature 214 of relay .21! is in a neutral. position, butshould the web W wander laterally in one direction or the other thearmature 214 moves in one or another of two directions and suppliespower to the armature of the motor 218 to. make it rotate in one or theother direction.

In this embodiment of the invention of Fig. 39 it is important that thevoltage, drop across the resistor 265 be independent of the s ed oftravel of the web W and this fact should be taken into consideration inthe design of. the amplifier 263. Also, it is apparent that the lateral,wandering is limited by the width of the row of images 259 and,

therefore, this embodiment is intended primarily for application tocases in which great wandering does not occur.

The word web, as used herein, is meant to be inclusive of sheet-likematerial. of any and all compositions. For example, the web may comprisepaper, cloth, Cellophane, metallic foils, rubber sheets, and the like.

The term photoelectric cell, as used herein, is meant to be. inclusiveof. any'and all photosensitive or other'radiation detecting devices,such as .the so-called soft or'ga's-filled tubes, the so-called"electron multiplier? tubes, bolometers, -ph'otolytic cells, seleniumcells,,and like devices.

It may here be pointed out that photosensitive devices are essentiallydetectors of radiation. Thus, the radiations usable in the presentinvention are not confined to visible light rays, but may includeinfra-red rays and ultra-violet rays, providing these radiations are notharmful to the material of the .web, and provided suitable radiationdetectors are used. All of such radiations are comprehended to be withinthe scope of the term "light" as herein used.

Some of apparatus herein described is claimed in the United StatesPatent 61' Donald C. Stockbarger, No, 2,203,706, dated June 11, 1940,for Method of and apparatus for maintaining web alignment; in theapplication of John L.

September 13, 1940, for United States patent on.

Compensating roll drive mechanism.

In all of the description heretofore given, the invention has beenrelated to printing presses and their control. However, it has beenintimated that the control systems of the invention are applicable toother machinery than printing presses.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

We claim: 1. In an alignment detector for use in connection with amoving web which carries thereon a row of periodically repeating patternbands of 'uniform spacing, said bands having different light reflectiveand/or transmissive characteristics than the surrounding portions of theweb, the provision of a plurality of optical systems effecting elongatedlight images parallel to the bands on the moving web, said opticalsystems comprising light sources with elongated filaments and focusingmeans between the filaments and the web, and photoelectric meansresponsive to the difierence in efiect between coincidence andnoncoincidenc'e of said image with respect to said pattern bands, thedistances between the .tions of the web, said groups having blank spacesand greater than the blank space between said groups, and photoelectricmeans responsive to the difference in effect between coincidence andnoncoincidence of said images with respect to said pattern bands.

4. In an alignment detector, a moving web which carries thereonrepeating groups of rows of printed bands of uniform spacing ultimatelyto form pages according to said groups, said bands individually havingdifierent light reflective and/or transmissive characteristics than thesurtween coincidence and noncoincidence of either of said images or bothwith respect to said pattern bands.

5. In an alignment detector, a moving web which carries thereonrepeating groups of printed lines of words oi. uniform spacing betweenimages being equal to the distance between a certain plurality of saidbands.

2. In an alignment detector for use in connection with a moving webwhich carries thereon a row ofperiodically repeating pattern bands ofuniform spacing, said bands having different light reflective and/ortransmissive characteristics than the surrounding portions of the web,the provision of a plurality of optical systems providing elongated'light images parallel to the bands on the moving web, singlephotoelectric means responsive to the difference in eflfect betweencoincidence and noncoincidence of said images with respect to saidpattern bands, the distances between the images being equal to thedistance between a predetermined plurality of said bands, and a controlcircuit responsive at all times to impulse from said photoelectricmeans.

3. In an alignment detector, a moving web which carries thereonrepeating groups of rows of printed bands, of uniform spacing, saidbands having diflerent light reflective and/or transmissivecharacteristics than the surrounding porlines, said groups forming thesubstance of pages to be cut from the web and respectively carrying thewording of said groups, said bands individually having difierent lightreflective and/ or transmissive characteristics than the surroundingportions of the web, said groups having blank spaces therebtweenproviding for page separation, an optical system providing at least twolight images on the moving web, the distance between the images beingequal to the distance between a predetermined plurality of said lines ofwords and greater than the blank space between said page groups, andphotoelectric means responsive to the diiference in effect betweencoincidence and non-coincidence of either or both of said images withrespect to said lines of words.

6. In an alignment detector, a moving web which carries thereonrepeating groups of rows of printed bands of uniform spacing, said bandshaving different light reflective and/or transmissive characteristicsthan the surrounding portions of the web, said groups having blankspaces therebetween, an optical system providing at least two lightimages on the moving web, the distance between the images being equal tothe distance between a predetermined plurality of said individual bandsand greater than the blank space between said groups, a singlephotoelectric eye, a second optical system simultaneously transmittingto said eye the light effects caused by coincidence and non-coincidenceof each of said images with respect to said pattern bands.

DONALD C. STOCKBARGER. JOHN L. JONES.

